The present invention relates to a mixing apparatus for use in blending two or more viscous liquids, such as rubber or plastic, and more particularly, to a mixing apparatus for such use, the apparatus having two rotors rotating on two rotary shafts, commonly called a two-axes type kneader. More specifically, the present invention relates to a mixing apparatus of two-axes type, wherein the two axes rotate in opposing directions.
The two-axes type kneader is well known and widely used, and the known kneader has a relatively long distance between the two rotary shafts to the extent that the distance is larger than the outside diameter of each rotor. Alternatively, when it is smaller than the diameter of the rotor, thereby allowing the two circulating paths to overlap in part, the angular and peripheral velocities of the two rotors are designed to be equal. In the former case, the mixing takes place mainly between the rotors and the inside walls of the vessel, but this system disadvantageously produces a relatively large space between the rotors. This space makes no substantial contribution to the mixing operation. In the latter case it can be thought that the larger the overlapping portions of the circulating paths are, the more these portions contribute to the mixing operation. However, it is required that the two rotors rotate at the same peripheral velocity. In addition, the materials to be mixed are introduced and withdrwn at the constantly same velocity, whereby no compressive force and/or no shearing force act on the materials being mixed. For these reasons it is difficult to enhance the mixing efficiency under the conventional mixing apparatus.